A procedure in which cells are taken from the inside of the airways that lead to the lungs. A bronchoscope (a thin, tube-like instrument with a light and a lens for viewing) is inserted through the nose or mouth into the lungs. A small brush is then used to remove cells from the airways. These cells are then looked at under a microscope. A bronchial brush biopsy is used to find cancer and changes in cells that may lead to cancer. It is also used to help diagnose other lung conditions. Also called bronchial brushing.